This invention relates to improved methods and apparatus for slitting and stamping metal strip, with particular reference to scroll-slitting a broad strip into narrower strips with profiled edges, followed by stamping in a high speed progression tooling press.
It is known to scroll-slit metal strip in broad coil form into a number of narrow strips on which the eventual components are, in effect, nested with those on adjacent strips in order to save material in producing parts with shapes such as circles or triangles; see for example U.S. Pat. No. 1,433,138 (P. Kreuse). A major difficulty with such machinery is obtaining very accurate feature spacing or wavelength, which is required if the resulting strips are to be fed to fixed feed length progression tools such as are used in the manufacture of electric motor laminations. This difficulty is addressed in my International patent application PCT/GB85/00347, which deals with the case of profiled edge cutters and steerable shearing rollers in particular.
It is also known to cut and slit sheet metal coil by radiation and energy beams such as laser and plasma. The positions of the beams may be controlled to close tolerances with respect to a relatively moving metal strip and reciprocated transversely to produce the required repetitive features.
My application PCT/GB85/00347 also addresses the problem of varying parameters of the input coil, such as temperature and tension, which may affect the resulting wave length.
A difficulty associated with the scroll-slitting process is that inherent stresses in a metal band are not necessarily uniform across the width and thus the slit strips may not all have the same feature spacing, due to varying amounts of stress relief which may be released during, or shortly after, the slitting process.